Atlas IIIB SEC

Atlas IIIB Single-Engine Centaur

Mission Profile

The Atlas IIIB SEC (Atlas IIIB Single-Engine Centaur) was a two-stage American launch vehicle in the Atlas family, featuring a Russian RD-180 first-stage engine and a single-engine Centaur upper stage for the heaviest commercial and government payloads. Standing 52.8 m tall with a 3.1 m core diameter and a liftoff mass of 225 tonnes, it generated 3,827 kN of liftoff thrust and could deliver 10,218 kg to low Earth orbit or 4,500 kg to geostationary transfer orbit. First flying in April 2003, the Atlas IIIB was a short-lived transitional variant that bridged the gap between the Atlas II and Atlas V, launching only a handful of missions before being superseded.